NOTE: This spoiler sent in by Chris, who says... "The movie was so well-done and well-acted, and Anne Hathaway delivers a performance that could land her an Oscar nod come January. I'll be surprised if the girl who played Hathaway's sister doesn't walks away with a nod as well.

The movie opens with Kym (Anne Hathaway) waiting outside the rehab center with a fellow patient Walter and a staff member named Rosa. Walter starts talking smack to Rosa, and Kym interferes. A car pulls up, and Rosa helps Kym to the car. Carol (Anna Deavere-Smith) and Kym's father Paul (Bill Irwin) pick her up. They catch up on things as they drive away. Kym's sister Rachel is getting married. Kym asks if mom will be there, and Paul assures Kym she will. After a while of driving, Kym asks to stop the car to get some Pepsi at a convenience store. As she walks in, the counter girl notices her and asks if she was on "Cops" They drive home where Kym meets and greets everyone. She then goes to meet her sister, Rachel (Rosemarie Dewitt), who is getting stylized by her maid-of-honor Emma (Anisa George). The sisters catch up on old times before Kym leaves the room and heads to hers. Kym asks when she is going to meet her fiancée, and Rachel says it will be this evening.

Later on in the day, Rachel tells her father she has to go to a meeting and to take a urine test. Paul cannot drive her down to the hospital, and the car's off limits. Kym rides a bike to the hospital, where she takes the test and then arrives late to the AA meeting, clumsily knocking over chairs and interrupting a man who was speaking. We hear a lot of testimonials, and then Kym goes home where Rachel introduces her to her fiancée Sidney (Tunde Adebimpe) and his best man Kieran (Mather Zickel). Turns out Kieran was the man she interrupted at the AA meeting.

Next we see Kym having sex with Kieran (his clothes are off while hers stay on) before she tries on the dresses Emma made. Kym gets angered and asks Rachel why she didn't choose her to be the made of honor, before complaining about the family being against her and figuratively commenting on "burning the house down". Rachel and Kym get in a little verbal argument, before Rachel bows to Kym's demands and asks Emma to step down from her role and become a bridesmaid. Emma is shocked, but complies (she holds a grudge to Kym for the rest of the movie).

The family is then seen at the rehearsal reception, where music and comedy routines are presented to Rachel and Sydney. They proceed to have the rehearsal dinner, where Kym feels like an outsider because of no one to talk to (whereas her sister tells her she's known basically everybody since eighth grade). Rachel and Kym finally meet and greet their mother, Abby (Debra Winger) when she arrives. Abby tries to talk Kym out of smoking during the party, to which she complies.

The testimonials are given by family members and friends. Kym is one of the last to speak, announcing herself as the "harbinger of doom" for the evening, and talks about her life in rehab and forgiveness being one of the 12 steps. Kym then apologizes to her sister and everybody for the harm she inflicted on them, then ends with a Hawaiian greeting.

When the family returns home, Rachel critiques Kym's apology while reading from the dictionary the meaning of the word. Paul tries to defend Kym 's actions, but Rachel talks right through him. Rachel and Kym get into an argument, in which it is revealed Rachel is pregnant, to which the family is overjoyed. Even though Kym is happy about the pregnancy, she gets mad for changing the topic before she walks away. Rachel states that she wishes Ethan was here to see this and that she is really tired.

The next day begins as Abby sits down with Rachel. Abby asks how everybody is doing, and how Kym is behaving. Rachel doesn't know how to answer that and Abby assures her that things will work out.

The scene cuts to Kym at the AA meeting, where she reveals that when she was 16, she was high on pills and accidentally ran her car off the overpass and into the river, killing her little brother Ethan, who she was baby-sitting. Kym then states that she is tying to forgive herself, and states she is on her own path.

Kym returns to her house with Kieran, who drives her home, as it begins to rain. The wedding tent has been raised up, as Rachel and her friends make the seating arrangements. Kym protests against sitting next to Grandma Rose, but their father Paul intervenes and seats her with the twins. Rachel excuses herself as she takes Paul in the kitchen to try and talk about Kym's recent behavior, but is quickly interrupted by Rachel's fiancée Sidney who challenges him to a dishwashing contest after Sidney critiques him on putting the dishes the wrong way. They set the challenge for 2 minutes, to which Sidney completes his task. It is Paul's turn, and is 15 seconds away from completing when he asks for more dishes. Kym hands him more, but Paul stops halfway and loses the bet. Paul appears at a loss for words as everybody sees what he was looking at. Everybody leaves the room, and Kym sees that one of the dishes she accidentally pulled out was the one that Ethan made. She quietly gets angry with herself and Sidney puts a hand on her back and quietly walks away. Kym is next seen putting all the dishes away.

Rachel and Kym go out later that day to get their hair and nails done. A dark man, whom she recognizes as being in one of her former AA classes, stops Kym. She is uncomfortable at first, but talks to him anyway. The man wants to thank her for changing his life, and refers to an activity they did in AA where members anonymously wrote down why they are here and passed it around. He got Kym's, and tells her that reading about her abuse at the hands of her uncle caused him to confront his own personal demons. Rachel overhears this and storms out in a rage, Kym in pursuit trying to apologize to her. Rachel drives away, leaving Kym stranded at the salon.

Paul asks Rachel what happened when she doesn't show up back at the house with Kym. Rachel has a talk with her father, saying that Rachel lies to everybody. Kym comes home and confronts Rachel, while Paul demands to know what is going on. Rachel reveals to Paul what she overheard. Paul asks if this is true. Kym states that it was one of her first times at a meeting, and she wanted to write something down that sounded interesting. Kym and Rachel exchange a verbal argument back-and-forth, until Kym finally storms out of the room. (From this scene, we learn that Paul is divorced from Abby and Carol is both Rachel and Kym's stepmother) The setup of the wedding goes on as planned, until Paul asks Rachel if she has seen her sister as it starts to turn into night.

Kym has taken the car and gone straight to her mother's new boyfriend's house (Carol is Kym's stepmother). Kym confronts her mother as to why she left the family in the first place. The two women get into a little scuffle and Abby slaps Kym. Kym is shocked by the fact her mother slapped her, and hits her back. Kym gets back in the car and leaves, crying. She speeds up the car and drives it into a sign and into the forest. The car smacks into a tree, deflating the air bag. She spends all night in the car as runners come to her rescue early morning.

A bruised Kym gets a ride from a friendly tow-trucker who drops her off across from her house. Paul and Carol open the door, worried, but there is no time as the wedding is minutes away. She goes up the stairs and knocks on Rachel's door. Rachel opens the door and helps Kym get ready for the big event.

The next scene is at the wedding, where Sidney is waiting for his bride. The music plays and Paul walks in with Rachel. Rachel and Sidney both say their vows (and Sidney sings a chorus of Neil Young's "Unknown Legend"). The two share a kiss and everyone dances after the wedding. Kym looks around for Abby as the party drags on into the night.

Kym walks by the moonlight and sees Rachel and Sidney dancing. She joins in and asks Rachel if she's seen Abby. Kieran joins and the four of them dance together before Abby comes in with her new fiancée Andrew. Abby is saying her good-byes as she is flying to Washington in the morning. The sisters are both speechless, but they wish her luck anyway. Kym excuses herself as Abby & Andrew exit the house. Kym is stopped by Paul, who introduces her to a woman who is opening a law firm in the Connecticut area, and she gives Kym her business card. Kym excuses herself to see her mother's car leave the driveway.

The next day Kym wakes up and packs, ready to go back into rehab. She says good-bye to Kieran, who gives her his phone number and she promises to visit him in Hawaii. They share a good-bye kiss before Rosa's car approaches. Rachel comes out to greet Rosa and says her farewells to Kym. Rachel watches as the car drives off. She goes back in the house and watches the tent being taken down as the credits roll.